Istratrix of said arthltr j



(No Model.)

A. J. HOLT, Decd.

F. S. HOLT, Administratrix. REGULATOR FOR DYNAMO ELECTRIC MACHINES.

Patented Jan. 29, 1889.

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UNITED STATES PATENT Grrrcn.

ARTHUR J. HOLT, OF GRAND RAPIDS, MICHIGAN; FRANCES S. HOLT ADMIX- ISTRATRIX OF SAID ARTHUR .I. HOLT, DECEASED.

REGU LATOR FOR DYNAMO-ELECTRIC MACHIN ES.

SPECIFICATION forming part of Letters Patent N 0. 396,932, dated January .29, 1889. Application filed May 13, 1884- Serial No.131,391. (N model.)

To aZZ whom it may 00716 these two corresponding points will in general Be it known that I, ARTHUR .I. HOLT, of j be found equally distant from the point or Grand Rapids, in the county of Kent and I a. If two such points, as at?) b,bebridgedby State of Michigan, have invented certain new a conductor, C, it is obvious that no current and useful Improvements in Dynamo-Elecwill flow; but it, on the cont my, the bridge trio Machines; and I do hereby declare the be connected at points if U, as shown by the following to be afull, clear, and exact descripdotted lines, or connected in any way to two tion of the invention, such as will enable othpoints of diiterent potential, it is evident that ers skilled in the art to which it pertains to a current must tlow from the point of higher make and use the same. 1 to the point of lower potential through the My improvements relate to dynamo-electric l bridge; and it is also evident that the inmachines in which the field is energized, in tensity of this current will gradually increase 41016 111 P t a e \'at mor shunt as the points I) Z) approach the points a a. from the main circuit. Such machines comi It, now, the bridge-wire C be made to include I 5 prise the two classes, shuntwount and the field-coils F, we will have a construction compound,or shunt and series wound, of machine which, from its ai'ialogy to the and my invention, which applies to both lVheatstone bridge, may be appropriately classes, consists, essentially, in so connecting termed bridge-wound, and which, while rethe field-magnet circuit to the armature and taining all the advantages of a shunt-wound 20 external circuits as to dispense with the large machine possesses none of its disadvantages. 7o amount of fine wire usually placed on the My invention is most easily applied to an field-magnets of such machines, and at the armature of the Gramme or Siemens type, same time to allow of a perfect regulation of and, as shown in Fig. 2, I prefer to derive the such machines without the aid of useless re- 1 field-current from the armature by a supple sistances. These objects I attain by so conf mentary pair of connmitator-brushes, D D, necting the field-circuit to the armatnre-cirthe main commutalorbrushes E E supplying cuit that the difference of potential at the reonly the external circuit, G. B represents spective ends ot' the field-circuit can be varied the ordinary ("rramme commutator. at will from a maximum equal to the total i It will be seen that by rocking, either by 30 electro-motive force furnished by the mahand or automatically, the simplementary 8o chine down to zero, preferably keeping it at i brushes D D it is possible to obtain anydifa point considerably below the maximum. ference of potential between the ends of the The application of my invention will be field-coils within the working-limitsof the best understood by reference t i the accompa- 1 machine, and thus provide a perfect regulanying drawings, in which 3 tion of the machine, whether it be used as a Figure l is a diagram illustrating the prinmotor or a generator, thus doing-away enciple of myinvention. Fig. Qshows a dynamo tirely with the use of resistances for regulatwith my invention applied,thc circuit-connecing the field-circuit. Fndcr certain circumtions being shown diagrammatically. Figs. stances the machine will be self-regulating 4o 3, r, and 5 show modified applications. Fig. after once obtaining the proper position of 0 I 6 shows the application of the invention to a the supplementary brushes for the particular machine of the compound type. installation. in which the machine is used.

Referring to Fig. 'l, A represents a Hramme Moreover, it will be seen that as the differring, and a (1, itspoints otm'aximum and mini- 3 once of potential at the extremities of the 45 mum potential where the current enters and field-coils can by my method be made norleaves the ring by the main commutatormally much lower than that of the main brushes. Now,asthe rise of potentialin thetwo brushes, there will be no need of using fieldhalves of the ring correspoml, there is for coils of high resistance in order to cut down every point on one side a corresponding point t the current in the field-circuit, for by suita- 50 on the other side of the same potential, and E bly proportioning the relations of the resis ance, number of convolutions, and strength of current, coarse wire may be used.

I have found serious objections to the use of high-resistance field-coils. In the first place the cost is very great; secondly, it being necessary to use just as thick insulation on the fine wire as on the coarse, the amount of space taken up by the insulation is very much greater in the fine-wire coil, correspondingly lessening its magnetic effect with a given current; thirdly, in an ordinary shunt-wound or compoundavound machine the extra current, which occurs it the circuit is broken, is of such high electro-niotive force as to cause a discharge of current between some points of weaker insulation with more or less danger to the machine. This danger renders necessary the use of even thicker insulation than would otherwise be required.

Although I prefer the bridge method of deriving the field-current, as shown in Fig. 2, it evidently lies within the scope of my invention to place both of the supplementary brushes on one side of the commutator, as shown in Fig. 3, or to use but one such brush, as shown in Fig. at, the other terminal of the field-circuit being connected to one of the main brushes. Fig. 5 shows practically the same construction as Fig. 4, with another supplementary brush connected with the other main brush, so as not to disturb the electrical balance of the armature. In this case there are two field-magnet circuits, F and F, which might, in the construction shown in Fig. 2, be placed one on each leg of the magnet. In Fig. G is shown an application of my invention to a 1 machine of the compound type. In this machine the field-coils F are in series with the armature and external circuit, and act in conjunction with the field-coils F,which are connected with the armature by supplementary brushes, according to my present invention,

as described above.

It will be seen that in the bridge method the current in the field may not only be reduced to zero, but maybe reversed by giving sui'iicient motion to the supplementary brushes. This would render the machine especially applicable for motive purposes.

Other combinations involving my invention may obviously be made, and I do not wish to con line myself to the speci n'c constructions shown.

Having thus described my invention, I claim as new In a compound-weund dynamo-electric machine, the combination,with the commutator, of commutator-brushes connected to the tield-' coils included in series with the armature and external circuit, and independently-adjustable commutator-brushes connected with the field-coils in derived circuit and located on the commutator at points intermediate between the points of maximum and minimum potentialot' the armature,substantially as set forth.

In testimony whereof I sign this specification, in the presence of two witnesses, this 5th day of illay, i884.

ARTHUR J. HOLT.

\Vitnesses: V

EDwARD TAGGART, FRED W. STEVENS. 

